Cross platform chat app Viber has launched version 4.1 for Android and iOS, plus a service that lets users call regular telephones and mobile phones from within the mobile and desktop app.

Competition in the mobile chat app market is getting into high gear, as Viber launches its latest app for Android and iOS. Version 4.1 for both platforms comes with a new calling service that enables the 200 million or so Viber users to call landlines and mobile phones around the world.

The Viber Out service was actually launched as an initial test in the recent weeks, along with its launch of push-to-talk and a new sticker market. Co-founder and CEO Talmon Marco earlier told VR Zone that the public beta of Viber Out was done to “help our Philippine users,” particularly those affected by the devastation of typhoon Haiyan. With this final release, Viber is ready-to-market and set to compete head-on against the likes of Skype, which offers both free calling within their networks, as well as outbound calling to local and global destinations.

“Viber Out gives our millions of users a new way to use Viber and ensures that they can reach any contact at any time,” said Marco. The company’s focus at this time is to keep users “connected at the most affordable rates possible.”

Comparing Viber Out with SkypeOut — Skype’s own VoIP to PSTN calling service — the calling prices are significantly cheaper across international markets, with the difference being as much as 389 percent for a three minute call to the UK.

One stark difference that Viber Out has from Skype is that it uses the caller’s actual caller ID, making it easier to connect with known contacts. Viber also syncs its address book across desktop and mobile, so calling from the desktop interface will not require re-entry of telephone numbers.

Apart from the calling service, Viber 4.1 also introduces new additions to Viber’s premium sticker market, which are a popular feature in certain regions. This particular aspect of Viber competes against the likes of LINE and KakaoTalk, two popular chat apps originating from Asia that have launched as platforms for social networking, gaming and both free and premium content.

Viber is a free download on the iTunes App Store and Google Play. Viber Out support for Windows Phone is planned in an upcoming update.